Partners in Global Health Education 1.How to use this module 2.Learning outcomes 3.Anatomy and function of skin 4.Local effects of burn injury 5.Systemic.

Partners in Global Health Education

1. How to use this module

2. Learning outcomes

3. Anatomy and function of skin

4. Local effects of burn injury

5. Systemic effects of burn injury

6. Assessing the burn surface area

7. Assessing the depth of the burn

8. Classification of burn injury

9. Information Sources

10. End of Module Quiz

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Burns

Welcome to the burns module!

Burns constitute a major global problem and are a leading cause of trauma deaths in children. Minor burns, if poorly treated, cause devastating complications with lifelong morbidity.

Understanding how burns cause tissue damage and how the skin heals is vitally important in ensuring that the right diagnosis is made and the right treatment given.

Typical burns from hot water in a child

For information about the authors of this module, click here












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How to use this module

• This self - directed learning (SDL) module has been designed

for medical and other health care students.

• We suggest that you start with the learning objectives and try

to keep these in mind as you go through the module slide by

slide, in order and at your own pace.

• You should research any issues that you are unsure about.

Look in your textbooks, access the on-line resources

indicated at the end of the module and discuss with your

peers and teachers.

• Finally, enjoy your learning! We hope that this module will be

enjoyable to study and complement your learning about burns

from other sources.












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Learning outcomes

By the end of the module, you should be able to:

• describe the structure of the skin

• outline the local and systemic effects of burn injury

• assess the size of burns accurately

• assess the depth of burns accurately and relate how

this determines the way in which it heals

• classify burn injuries according to the type of

treatment required (outpatient, inpatient or specialist

care)












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Anatomy of skin (1)

Epidermis

Dermis

The skin is made up of two layers, the outer layer (epidermis) and inner layer (dermis). Between the epidermis and dermis is the basement membrane which is semi permeable and acellular. It provides support, flexibility and regulates the transfer of substances across the dermal-epidermal junction.

Under the skin is the subcutaneous layer which allows the skin to be loosely attached to the underlying fascia. It increases mobility and is especially important over joints.

basement membrane

Subcutaneous layer












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Anatomy of skin (2)

Thickness of skin increases from birth until approximately 40 years of age, then it starts to thin again. It also varies over different parts of the body.

The eyelid has a thin epidermis (~0.05mm). The palm and foot have a thick epidermis (>1.5mm).

Click to Reveal AnswersClick to Reveal Answers

Which of the following areas do you think has a thin epidermis?:

a. Eyelidb. Palmc. Foot












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Anatomy of skin – Epidermis (1)

A protective barrier of stratified squamous epithelium consisting of 5 layers1. Stratum corneum: 20-30 rows

of dead cells continually shed2. Stratum lucidum: 3-4 layers

clear flat dead cells3. Stratum granulosum: Cells

degenerating with production of keratin

4. Stratum spinosum: 8-10 rows of cells that produce protein but can not duplicate

5. Stratum basale: Columnar cells continually dividing, gradually migrating to surface

EPIDERMIS

There are three other cell types within the epidermis: melanocyte, Langerhan and Merkel cells












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Anatomy of skin – Epidermis (2)

Other cell types within the epidermis:

1. Melanocytes: Produce melanin pigment causing brown colouration of skin and protects skin from UV light damage

2. Langerhan cells: Immune cells which help in defence. Situated in stratum spinosum, they help process and present foreign antigens to the immune system

3. Merkel cells: Within the basal layer, close to hair follicles; involved in touch sensation

Who do you think has more melanocytes (a), (b) or (c)?


None of them! All racial groups have the same

number of melanocytes, but dark skin individuals have more metabolically active cells which produce more

melanin.

(a) (b) (c)












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Anatomy of skin – Dermis (1)

The dermis consists of 2 layers:• Papiliary dermis: The upper layer of

dermis. It has extensions protruding into the epidermis called Rete pegs which also contain small capillary loops

• Reticular dermis: The lower layer of dermis. It is made up of collagen, elastin and ground substance as well as hair follicles, sweat and sebaceous glands

Fibroblasts are the predominant cell type in the dermis and produce collagen and elastin which provide strength and flexibility to the skin.

In addition, there are blood vessels, sebaceous glands, sweat glands, hair follicles, sensory receptors and fat cells.












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Anatomy of skin – Dermis (2)

There are other cell types and structures within the dermis:

• Myofibroblasts - contractile, important in healing of wounds

• Macrophages - derived from vascular leucocytes;

phagocytic and stimulate fibroblasts

• Mast cells - contain histamine

• Lymphocytes - mediate immune function

• Sensory receptors

Meisners Khause Ruffins Paccinian

Texture Cold Heat Vibration & deep

pressure












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Functions of the skin

Physical barrier

Temperature control

Immunity

Sensation

Vitamin D production

Identity

Remember P V I S I T !












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Local effects of burn injury (1)

Summary of local effects:– Cell death/disturbed function– Release of inflammatory mediators– Increased capillary permeability– Microvascular thrombosis

1. Cell death/disturbed function

Cellular function is disturbed when the temperature rises above 43oC. The higher

the temperature and more prolonged the contact, the more cells die. An

instantaneous full thickness burn occurs at a temperature of 700C or greater.

Due to differences in skin thickness with age, at 55C, severe damage occurs after 10 seconds in a child and 30 seconds in an adult. Skin thickness is also reduced in older people and in certain conditions (e.g. steroid therapy).












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2. Release of inflammatory mediators

Potent vasoactive mediators are released from the burn wound. These include

vasoconstrictors and vasodilators, histamine, serotonin, kinins, prostaglandins

and oxygen free radicals

• Thromboxane: causes platelet aggregation and microvascular thrombus formation

• Histamine: released by mast cells; causes increase in capillary permeability

• Prostaglandins: result in arteriolar dilatation

• Kinins: increases vascular permeability

• Serotonin: increases vascular resistance and venous hydrostatic pressure leading

to oedema

• Oxygen free radicals: increase vascular permeability












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3. Increased capillary permeabilityWhen capillaries are damaged, they leak protein-rich fluid which results in oedema.

Normal skin; normal capillary permeability

Burn wound oedema with increased capillary permeability

and protein leakage












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4. Microvascular ThrombosisRelease of thrombogenic factors such as thromboxane, together with a hypovolaemic state cause sludging in the smallest blood vessels. This in turn leads to further tissue ischaemia, increased cell death and can cause extension of the depth and surface area of the burn.

Area of burn increases due to sludging in blood

vessels and ischaemia












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Systemic effects of burn injury (1)

When a burn is large (>20% of total body surface area), in

addition to the local response, there is also a systemic

response

Vasoactive substances are released that act not just locally

in the burned tissue, but in non-burned tissue as well.

With large burns, the loss of

circulating blood volume

will rapidly lead to

HYPOVOLAEMIC

SHOCK, unless

resuscitation is started

Loss of circulating

blood

Vascular permeability

Ischaemia












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Systemic effects of burn injury (2)

Click each box

Respiratory system

Cardiovascular system

Renal system

Haematological system

Immune system

Psychological system

Gastrointestinal system












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Assessing total burn surface area (TBSA)

The area of this burn is about 3-5% of total body surface area.

How much of the body surface area is burnt?

There are several ways to assess the size of a burn. They all consider the burnt area as a percentage of the total body surface area and are supported by mapping the burnt area on a diagram. In the next couple of slides, we will be looking at the following methods of assessment:

1. The rule of 9’s

2. Lund and Browder charts

3. Palm of hand

4. Unburnt area













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Assessing TBSA - Rule of Nines

This method divides the body into areas each of which

equates to 9% of the total body surface area:

• the whole of one arm (anterior and posterior surfaces

including the hand) is 9%, therefore 2 arms = 18%

• the entire head including face, scalp and neck is 9%

• anterior trunk is 18%

• posterior trunk including buttocks is 18%

• the whole lower limb (anterior and posterior surfaces,

including the thigh, leg and foot) is 18%; therefore both lower

limbs = 36%.

This totals 99% with the perineum making the final 1%.

Beware: this method is unreliable in young children.












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Assessing TBSA in children

Why might the “rule of 9’s” be unreliable in children?

Body proportions change with age. In a child, the head represents a much greater proportion

of the total body surface area.Click to Reveal AnswersClick to Reveal Answers












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Assessing TBSA - Lund and Browder charts

These take account of the

patient’s age and provide a

more detailed mapping system

for the burnt area

AREA AGE 0 1 5 10 15 ADULT

A = ½ OF HEAD 9 ½ 8 ½ 6 ½ 5 ½ 4 ½ 3 ½

B = ½ OF ONE THIGH 2 ¾ 3 ¼ 4 4 ½ 4 ½ 4 ¾

C = ½ OF ONE LEG 2 ½ 2 ½ 2 ¾ 3 3 ¼ 3 ½












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Assessing TBSA - Palm size

Another useful way, especially for small burns is to use the palm of the patient’s hand (with fingers extended). This equates to approximately 1% of the body surface area.












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Assessing TBSA - Unburnt area

In very large burns, it is often easier to measure the area of skin that is unburnt and then subtract this from 100%.












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Circumferential burns of the limbs can cause distal ischaemia; of the chest, can compromise breathing

Area of the body involved

Not only is the surface area or size of burn important, but also the specific part of the body affected

Face: Facial oedema can lead to airway obstruction. Scarring can cause significant psychosocial problems

Perineum: problems with urogenital function and psychosexual

Hands: Problems with feeding and hygiene

Feet: Mobility problems

Eyes: Burns to the eyes (especially chemical) can cause blindness.












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Depth of burn

The depth of a burn determines its treatment and how long it takes to heal.

For this reason, it is important to be able to assess the depth as:

Superficial

Partial thickness

• Superficial partial thickness

• Deep partial thickness

Full thickness












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Depth of burn - Superficial (erythema)

Involves epidermis only:

• Painful

• Red

• No blistering

• Heals rapidly (reversible injury)

• No permanent scars

Note that erythema is NOT included when assessing TBSA












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Depth of Burn – superficial partial thickness

Patches of skin that would come off on cleaning

Glistening moist red/pink

appearance typical of superficial injury

Typical hot water scald

Involves epidermis and upper dermis:

• Red

• Blistering, moist

• Painful

• Heals by epithelialization

• Healing complete within 14 days

• Minimal or no permanent scars

but can leave discolouration












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Depth of Burn - superficial partial thickness

Blister

Pin-point bleeding

Pink surface; blanches on

pressure












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Depth of Burn – deep partial thickness

Involves epidermis, upper dermis and varying degrees of lower dermis:

• Pale, mottled appearance

• Fixed staining (no blanching)

• May be painful or insensate (depending on depth)

• Heals by combination of epithilialization and wound contracture

• May take weeks to heal

• Can leave significant scars and contractures over joints depending on time taken to heal

Deep dermal area, reddish with fixed staining












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Depth of Burn – full thickness

• Involves all of epidermis and all of dermis

• Dry, leathery (white, dark brown or charred)

• Insensate

• Heals by contraction

• Delayed healing

• Hypertrophic or keloid scars

• Leads to contractures Dry, leathery, charred appearance of a full

thickness burn












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Circumferential full thickness burn

Typical position of hand in full thickness

burns with metacarpophalangeal joints extended and

interphalangeal joints flexed

Black, charred skin












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Depth of Burn – mixed thickness

Assess the depth of the

burn in areas A, B and C

( C )(B)

(A)













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Depth of Burn – Mixed thickness

Deep dermal with pale pink and white patches, non blanching

Superficial partial thickness showing pink blanching

Full thickness, dry white leathery appearance












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Classifying the patient

First you should assess the severity of the burn injury according to• TBSA• depth• position• presence of infection• time since the burn• presence or absence of inhalation injury

Combine this information with patient factors:• age • associated injuries• other medical problems• nutritional status

Finally consider social and family factors to classify the patient according to how and where to provide treatment.












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A guideline for patient classification

significantnone• other medical problems

SpecialistIn-patientOut-patient

Social / family factors

• nutritional status

significantnone• associated injuries

Extremes of ageAdult or older child• age

Patient factors

severemildAbsent• inhalation injury

Critical areaNon-critical area• position

• presence of infection

• depth

• TBSA

Burn injury

Factors

Small Moderate Large

Superficial Partial thickness Full thickness

Absent Localised Systemic

Normal Malnourished

Able to care for oneself Unable to care for oneself












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Sources of information

• Some images have been adapted from CorelDraw clipart

• See www.interburns.org for more information












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End of Module Quiz

Well done!Now that you have completed the burns module you may wish to try these questions to assess

your learning.

First, print-out the questions and write down your answers to each one.

Then look at the answer sheet to assess your learning.

QuestionsQuestions AnswersAnswers

Partners in Global Health Education 1.How to use this module 2.Learning outcomes 3.Anatomy and function of skin 4.Local effects of burn injury 5.Systemic.

Documents

classification of burn

burns module

local effects of burn

burn injuries

module slide

burn surface area

learning sdl module

function of skin